Automatic cut off switch



T. D. HOPKINS AUTOMATIC OUT-OFF SWITCH Filed Aug. lO. 1932 W 92 7 ,9% z Z 4/ MJ! /fw z z w ,w g .f 8 aw w Z z z z w z ,w

Sept. 5, 1933.

Patented Sept. 5, 1933 STATES PATENT oFFlcE 3 Claims.

This invention relates to automatic switches and more particularly to an automatic cut-off switch adapted for use withV diagnostic means Z such as ophthalmoscopes, retinoscopes or the like.

Another object of this invention is to provide a switch of this Character which is so constructed that it will be normally urged into open position toV prevent burning out of the light within the device.

A further object of this invention is to provide a switch construction such that, if desired, the automatic cut-off means can be held against operation'so as to permit the light bulb within the device to be burned continuously. i

A still further object of this invention is to provide a switch construction for use in a device of this kind whereby a slight pressure on the head or Operating end of the device will close the switch and when the pressure has been released, the switch will automatically move into open position.

The above and various other objects and advantages of this invention will in part be described and in part be understood from the following detailed description of the present preferred embodiment, the same being illustrated in the accompanying drawing whereinz- Figure 1 is a detail side elevation partly in section of a device constructed according to the preferred embodiment of this invention.

of reference designate corresponding parts throughout the several views, the letter I-I designates generally the head of a retinoscope or the like which has a handle removably secured thereto. This handle 10 has a socket 11 within which a light bulb 13 is mounted and the light from this bulb 13 is refiected toward the open I end of the head H. This head H is of Conventional and well known construction.

A plug or cap member 12 is threadably mounted on the inner end of the handle 10 and conductor wires 14 and 15 extend through this plug or cap 12. A tube 16 is disposed longitudinally of the handle 10 and the conductor wire 15 is electrically connected with the inner end of a rod 17 which is slidably mounted within this tube 16.

A second tube or conductor 19 extends in a div rection parallel to the tube 16 and this conductor 19 is electrically connected with the Wire 14 and is provided with an inner or fixed contact 18. The opposite ends of the wires 14 and 15 are adapted to be connected to a source of electric current supply. The outer end of the handle 10 is provided with 'a fianged cap 20, the fiange 20SL of which is preferably slightly smaller in diameter than the diameter of the cap, and the head H is provided with an annular fiange 21 which is adapted to removably engage the fiange 20a. The fiange 20a is provided with a'pair of openings 22 and a spring 23, which is secured, as at 24, to the fiange 20a, has 'an end portion thereof disposed in and extending through the openings 22, thereby providing resilient pins or head securing members 25.

The flange 21 of the head H is provided with a pair of L-shaped bayonet slots or detents 26 by means of which the head H can be removably mounted on the handle 10. In practice, there are two of these detents 26 and the fiange 21 is of a size relatively larger than the flange 20a so that it will be loosely mounted thereon.

A contact spring 27 is connected at one end to the socket 11 and the other end overlies the fixed contact 18 and is adapted to be engaged by a push pin 28 carried by the head H so as to be rocked by this head with the ends of the spring 23 as a fulcrum. The spring 27 normally holds the head H in inoperative position, but rocking of the head H with the spring ends 25 as a fulcrum will cause the spring 27 to engage the contact 28, thereby closing the circuit and lighting the bulb.

In order to provide means whereby the head H may be held in switch closing position, I have provided a set screw 29 which is mounted in the outer end of the handle 10 for movement toward or away from the confronting edge of the flange 21. Movement of the screw 29 toward the fiange 21 will cause the head H, when mounted on the handle 10, to be rocked in switch closing position and held in this position so as to light the bulb 13 continuously.

In practice, the handle 10 may be constructed of insulating material and the outer end of this handle be provided with an annular member of metal construction. i

In the use and operation of this device, the wires 14 and 15 may be connected to the desired current supply and the handle 10 grasped in the hand with a finger or thumb contacting with the head H which is held in a position to maintain the switch open by means of the resilient contact v spring 27.

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When it is desired to light the bulb, the head H may be rocked on the fulcrum formed by the end of the 'spring 23, thereby moving the spring 27 into engagement With the fixed contact 18. The bulb 23 will then be maintained in lighted form until the head His released -whereby the switch will automatically move into open position by the spring 27 forcing the pin .28V outwardly, thereby preventing the bulb from becoming burned out through excessive continuouse.

It is, of course, understood that various changes and modifications may be made in the details of construction and design of the'above specifically described embodiment of this invention Without departing from the spirit thereof, such changes and modifications being restricted onlyby the scope of the following claims.

It will be noted from the drawng that the system or method ofV connecting the light which is disposed within the headV H provides means whereby the handle 10 'may' be readilyhconnected or disconnected from a source of current supply and that the device maybe readily assembled tor taken apart so that it canpbe easily andquickly repaired in the event such repairs are necessary. Furthermore, by disposing the conductorsrl and 19 within the handle'in spaced relationgto each other, there is no possibility ofthe two conductors coming intov contact With eachV other'V except through the medium oftthe movable contact 27 thereby eliminating the possibility of 'a short circuit within the handle orzbody 10.-

The use of thebayonet slots'26and the members 25 provide means whereby the head H may be w taken off or put on in an instant so that various ;jing longitudinally through the handle, a socket connectedV to one of the conductors, a lamp in the "socket, a 'fixed'contact connected to the other of the conductors, a head, means for removably and rockably mounting the head on the outer end of the handle while substantially maintaining Vthe head in alinement with the handle, and a resilient movable switch arm connected to the socket and engaging the'head to rock the head in' one direction, movement of the head in the other direction swinging said resilient contact into engagement with the fixed contact to close the electric circuit to the light bulb.

3. A diagnostic means comprising a handle, a lamp in the handle, a head, means for rockably and removably mounting the head on the handle while substantially maintaining the head in alinementwith the handle, and a normally open switch arranged between the head and the handle and adapted to be closed upon rocking of the head, said mcunting means comprising a fiange carried by the handle, a second flange carried by the head and loosely engaging the first'fiange, said first fiange having a pairtof apertures therethrough spaced apart, a spring having outturned end portions extending through said apertures, meansior securing' the spring to the first fiange,

Vanddetents formed with the second flange for engagement with the ends of the spring to removably and rockably hold the head on the handle.

THOMAS DAVID HOPKIN S. 

